Oligomer-containing pyrrolidine compounds

ABSTRACT

The invention relates to (among other things) oligomer-containing pyrrolidine compounds. A compound of the invention, when administered by any of a number of administration routes, exhibits one or more advantages over corresponding compounds lacking the oligomer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/319,924, filed Jan. 9, 2012, which application is a 35 U.S.C. §371application of International Application No. PCT/US2010/034773, filed 13May 2010, designating the United States, which claims the benefit ofpriority under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationNo. 61/177,993, filed May 13, 2009, the disclosures of which areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

This invention comprises (among other things) chemically modifiedpyrrolidines that possess certain advantages over pyrrolidines lackingthe chemical modification. The chemically modified pyrrolidinesdescribed herein relate to and/or have application(s) in (among others)the fields of drug discovery, pharmacotherapy, physiology, organicchemistry and polymer chemistry.

BACKGROUND OF THE INVENTION

Epilepsy is a common chronic neurological disorder characterized byrecurrent unprovoked seizures. These seizures are transient signs and/orsymptoms of abnormal, excessive or synchronous neuronal activity in thebrain. About 50 million people worldwide have epilepsy, with almost 90%of these people being in developing countries. Epilepsy is more likelyto occur in young children or people over the age of 65 years; however,it can occur at any age. Epilepsy is usually controlled, but not cured,with pharmacotherapy, although surgery may be indicated in exceptionalcases. Despite the reliance on pharmacotherapy as the primary approachin controlling the disease, over 30% of people with epilepsy do not haveseizure control even with the best available medications. Not allepilepsy syndromes are life-long; some forms are confined to particularstages of childhood. Epilepsy should not be understood as a singledisorder, but rather as a group of syndromes with vastly divergentsymptoms, but all involving episodic abnormal electrical activity in thebrain.

Seizure types are organized firstly according to whether the source ofthe seizure within the brain is localized (partial or focal onsetseizures) or distributed (generalized seizures). Partial seizures arefurther divided on the extent to which consciousness is affected. If itis unaffected, then it is a simple partial seizure; otherwise it is acomplex partial (psychomotor) seizure. A partial seizure may spreadwithin the brain—a process known as secondary generalization.Generalized seizures are divided according to the effect on the body,but all involve loss of consciousness. These include absence (petitmal), myoclonic, clonic, tonic, tonic-clonic (grand mal) and atonicseizures.

There are over 40 different types of epileptic conditions, including:absence seizures, atonic seizures, benign Rolandic epilepsy, childhoodabsence, clonic seizures, complex partial seizures, frontal lobeepilepsy, febrile seizures, infantile spasms, juvenile myoclonicepilepsy, juvenile absence epilepsy, Lennox-Gastaut syndrome,Landau-Kleffner syndrome, myoclonic seizures, mitochondrial disorders,progressive myoclonic epilepsies, psychogenic seizures, reflex epilepsy,Rasmussen's syndrome, simple partial seizures, secondarily generalizedseizures, temporal lobe epilepsy, toni-clonic seizures, tonic seizures,psychomotor seizures, limbic epilepsy, partial-onset seizures,generalized-onset seizures, status epilepticus, abdominal epilepsy,akinetic seizures, auto-nomic seizures, massive bilateral myoclonus,catamenial epilepsy, drop seizures, emotional seizures, focal seizures,gelastic seizures, Jacksonian march, Lafora disease, motor seizures,multifocal seizures, neonatal seizures, nocturnal seizures,photosensitive seizure, pseudo seizures, sensory seizures, subtleseizures, Sylvan seizures, withdrawal seizures, and visual reflexseizures, among others.

Anticonvulsants are generally prescribed for the treatment ofindividuals suffering from or prone to epilepsy. Pyrrolidine compoundsrepresent one such class of compounds. Pyrrolidine compounds are alsoused in the treatment of individuals suffering from or prone toperipheral neuropathy, Tourette syndrome, autism, and anxiety disorder.Treatment of individuals with these compounds, however, is associatedwith many side effects, including: hair loss; “pins and needles”sensation in the extremities; anxiety and psychiatric symptoms rangingfrom irritability to depression; sleepiness; weakness; dizziness;infection; and other side effects like headache and nausea.

Therefore, pharmacotherapy with such therapeutic pyrrolidines would beimproved if these and/or other adverse or side effects associated withtheir use could be decreased or if their pharmacology may be improved.Thus, there is a large unmet need for developing novel pyrrolidinecompounds.

The present invention seeks to address these and other needs in the art.

SUMMARY OF THE INVENTION

In one or more embodiments of the invention, a compound is provided, thecompound comprising a pyrrolidine residue covalently attached via astable or degradable linkage to a water-soluble, non-peptidic oligomer.

The “pyrrolidine residue” is a compound having a structure of atherapeutically active pyrrolidine moiety that is altered by thepresence of one or more bonds, which bonds serve to attach (eitherdirectly or indirectly) one or more water-soluble, non-peptidicoligomers.

Exemplary compounds of the invention include those having the followingstructure:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical;

X¹ is a first spacer moiety;

X² is a second spacer moiety;

POLY¹ is a first water-soluble, non-peptidic oligomer; and

POLY² is a second water-soluble, non-peptidic oligomer.

Further exemplary compounds of the invention include those having thefollowing structure:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical;

R² is selected from the group consisting of hydrogen, an alkyl radical,an alkenyl radical, an alkynyl radical, a cycloalkyl radical, and anaryl radical;

X is a spacer moiety; and

POLY is a water-soluble, non-peptidic oligomer.

In this regard, any pyrrolidine moiety having anti-epileptic and/oranalgesic activity can be used as the pyrrolidine moiety from which thepyrrolidine residue is obtained. Exemplary pyrrolidine moieties have astructure encompassed by Formula I:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical; and

either R¹ and R² are each independently selected from the groupconsisting of hydrogen, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, aC₂₋₆ alkynyl radical, a C3-6 cycloalkyl radical, and an aryl radical,

or R¹ and R², together with the nitrogen atom to which they areattached, form a heterocyclic radical.

In the context of the present description (e.g., with respect tocompounds defined by each of Formula Ia-C, Formula Ib-C and Formula I),when (p) is defined as 6 and each “L” is defined as hydrogen, thecorresponding pyrrolidine group will have the following structure:

An exemplary pyrrolidine moiety for use in the current invention islevetiracetam.

In one or more embodiments of the invention, a composition is provided,the composition comprising a compound comprising a pyrrolidine residuecovalently attached via a stable or degradable linkage to awater-soluble, non-peptidic oligomer, and optionally, a pharmaceuticallyacceptable excipient.

In one or more embodiments of the invention, a dosage form is provided,the dosage form comprising a compound comprising a pyrrolidine residuecovalently attached via a stable or degradable linkage to awater-soluble, non-peptidic oligomer, wherein the compound is present ina dosage form.

In one or more embodiments of the invention, a method is provided, themethod comprising covalently attaching a water-soluble, non-peptidicoligomer to a pyrrolidine moiety.

In one or more embodiments of the invention, a method is provided, themethod comprising administering a compound to a mammal in need thereof,the compound comprising a pyrrolidine residue covalently attached via astable or degradable linkage to a water-soluble, non-peptidic oligomer.

Additional embodiments of the present conjugates, compositions, methods,and the like will be apparent from the following description, examples,and claims. As can be appreciated from the foregoing and followingdescription, each and every feature described herein, and each and everycombination of two or more of such features, is included within thescope of the present disclosure provided that the features included insuch a combination are not mutually inconsistent. In addition, anyfeature or combination of features may be specifically excluded from anyembodiment of the present invention. Additional aspects and advantagesof the present invention are set forth in the following description andclaims.

DETAILED DESCRIPTION OF THE INVENTION

As used in this specification, the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.

In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions describedbelow.

“Water soluble, non-peptidic oligomer” indicates an oligomer that is atleast 35% (by weight) soluble, preferably greater than 70% (by weight),and more preferably greater than 95% (by weight) soluble, in water atroom temperature. Typically, an unfiltered aqueous preparation of a“water-soluble” oligomer transmits at least 75%, more preferably atleast 95%, of the amount of light transmitted by the same solution afterfiltering. It is most preferred, however, that the water-solubleoligomer is at least 95% (by weight) soluble in water or completelysoluble in water. With respect to being “non-peptidic,” an oligomer isnon-peptidic when it has less than 35% (by weight) of amino acidresidues.

The terms “monomer,” “monomeric subunit” and “monomeric unit” are usedinterchangeably herein and refer to one of the basic structural units ofa polymer or oligomer. In the case of a homo-oligomer, a singlerepeating structural unit forms the oligomer. In the case of aco-oligomer, two or more structural units are repeated—either in apattern or randomly—to form the oligomer. Preferred oligomers used inconnection with present the invention are homo-oligomers. Thewater-soluble, non-peptidic oligomer comprises one or more monomersserially attached to form a chain of monomers. The oligomer can beformed from a single monomer type (i.e., is homo-oligomeric) or two orthree monomer types (i.e., is co-oligomeric).

An “oligomer” is a molecule possessing from about 1 to about 30monomers. Specific oligomers for use in the invention include thosehaving a variety of geometries such as linear, branched, or forked, tobe described in greater detail below.

“PEG” or “polyethylene glycol,” as used herein, is meant to encompassany water-soluble poly(ethylene oxide). Unless otherwise indicated, a“PEG oligomer” or an oligoethylene glycol is one in which substantiallyall (preferably all) monomeric subunits are ethylene oxide subunits,though, the oligomer may contain distinct end capping moieties orfunctional groups, e.g., for conjugation. PEG oligomers for use in thepresent invention will comprise one of the two following structures:“—(CH₂CH₂O)_(n)—” or “—(CH₂CH₂O)_(n-1)CH₂CH₂—,” depending upon whetheror not the terminal oxygen(s) has been displaced, e.g., during asynthetic transformation. As stated above, for the PEG oligomers, thevariable (n) ranges from about 1 to 30, and the terminal groups andarchitecture of the overall PEG can vary. When PEG further comprises afunctional group, A, for linking to, e.g., a small molecule drug, thefunctional group when covalently attached to a PEG oligomer does notresult in formation of (i) an oxygen-oxygen bond (—O—O—, a peroxidelinkage), or (ii) a nitrogen-oxygen bond (N—O, O—N).

The terms “end-capped” or “terminally capped” are interchangeably usedherein to refer to a terminal or endpoint of a polymer having anend-capping moiety. Typically, although not necessarily, the end-cappingmoiety comprises a hydroxy or C₁₋₂₀ alkoxy group. Thus, examples ofend-capping moieties include alkoxy (e.g., methoxy, ethoxy andbenzyloxy), as well as aryl, heteroaryl, cyclo, heterocyclo, and thelike. In addition, saturated, unsaturated, substituted and unsubstitutedforms of each of the foregoing are envisioned. Moreover, the end-cappinggroup can also be a silane. The end-capping group can alsoadvantageously comprise a detectable label. When the polymer has anend-capping group comprising a detectable label, the amount or locationof the polymer and/or the moiety (e.g., active agent) of interest towhich the polymer is coupled, can be determined by using a suitabledetector. Such labels include, without limitation, fluorescers,chemiluminescers, moieties used in enzyme labeling, colorimetricmoieties (e.g., dyes), metal ions, radioactive moieties, and the like.Suitable detectors include photometers, films, spectrometers, and thelike. In addition, the end-capping group may contain a targeting moiety.

The term “targeting moiety” is used herein to refer to a molecularstructure that helps the conjugates of the invention to localize to atargeting area, e.g., help enter a cell, or bind a receptor. Preferably,the targeting moiety comprises a vitamin, antibody, antigen, receptor,DNA, RNA, sialyl Lewis X antigen, hyaluronic acid, sugars, cell-specificlectins, steroid or steroid derivative, RGD peptide, ligand for a cellsurface receptor, serum component, or combinatorial molecule directedagainst various intra- or extracellular receptors. The targeting moietymay also comprise a lipid or a phospholipid. Exemplary phospholipidsinclude, without limitation, phosphatidylcholines, phosphatidylserine,phosphatidylinositol, phosphatidylglycerol, andphosphatidylethanolamine. These lipids may be in the form of micelles orliposomes and the like. The targeting moiety may further comprise adetectable label or alternately a detectable label may serve as atargeting moiety.

“Branched,” in reference to the geometry or overall structure of anoligomer, refers to an oligomer having two or more polymer “arms”extending from a branch point.

“Forked,” in reference to the geometry or overall structure of anoligomer, refers to an oligomer having two or more functional groups(typically through one or more atoms) extending from a branch point.

A “branch point” refers to a bifurcation point comprising one or moreatoms at which an oligomer branches or forks from a linear structureinto one or more additional arms.

The term “reactive” or “activated” refers to a functional group thatreacts readily or at a practical rate under conventional conditions oforganic synthesis. This is in contrast to those groups that either donot react or require strong catalysts or impractical reaction conditionsin order to react (i.e., a “nonreactive” or “inert” group).

“Not readily reactive,” with reference to a functional group present ona molecule in a reaction mixture, indicates that the group remainslargely intact under conditions that are effective to produce a desiredreaction in the reaction mixture.

A “protecting group” is a moiety that prevents or blocks reaction of aparticular chemically reactive functional group in a molecule undercertain reaction conditions. The protecting group may vary dependingupon the type of chemically reactive group being protected as well asthe reaction conditions to be employed and the presence of additionalreactive or protecting groups in the molecule. Functional groups whichmay be protected include, by way of example, carboxylic acid groups,amino groups, hydroxyl groups, thiol groups, carbonyl groups and thelike. Representative protecting groups for carboxylic acids includeesters (such as a p-methoxybenzyl ester), amides and hydrazides; foramino groups, carbamates (such as tert-butoxycarbonyl) and amides; forhydroxyl groups, ethers and esters; for thiol groups, thioethers andthioesters; for carbonyl groups, acetals and ketals; and the like. Suchprotecting groups are well-known to those skilled in the art and aredescribed, for example, in T. W. Greene and G. M. Wuts, ProtectingGroups in Organic Synthesis, Third Edition, Wiley, New York, 1999, andreferences cited therein.

A functional group in “protected form” refers to a functional groupbearing a protecting group. As used herein, the term “functional group”or any synonym thereof encompasses protected forms thereof.

A “physiologically cleavable” or “hydrolyzable” or “degradable” bond isa relatively labile bond that reacts with water (i.e., is hydrolyzed)under physiological conditions. The tendency of a bond to hydrolyze inwater may depend not only on the general type of linkage connecting twocentral atoms but also on the substituents attached to these centralatoms. Appropriate hydrolytically unstable or weak linkages include butare not limited to carboxylate ester, phosphate ester, anhydrides,acetals, ketals, acyloxyalkyl ether, imines, orthoesters, peptides,oligonucleotides, thioesters, and carbonates.

An “enzymatically degradable linkage” means a linkage that is subject todegradation by one or more enzymes.

A “stable” linkage or bond refers to a chemical bond that issubstantially stable in water, that is to say, does not undergohydrolysis under physiological conditions to any appreciable extent overan extended period, of time. Examples of hydrolytically stable linkagesinclude but are not limited to the following: carbon-carbon bonds (e.g.,in aliphatic chains), ethers, amides, urethanes, amines, and the like.Generally, a stable linkage is one that exhibits a rate of hydrolysis ofless than about 1-2% per day under physiological conditions. Hydrolysisrates of representative chemical bonds can be found in most standardchemistry textbooks.

“Substantially” or “essentially” means nearly totally or completely, forinstance, 95% or greater, more preferably 97% or greater, still morepreferably 98% or greater, even more preferably 99% or greater, yetstill more preferably 99.9% or greater, with 99.99% or greater beingmost preferred of some given quantity.

“Monodisperse” refers to an oligomer composition wherein substantiallyall of the oligomers in the composition have a well-defined, singlemolecular weight and defined number of monomers, as determined bychromatography or mass spectrometry. Monodisperse oligomer compositionsare in one sense pure, that is, substantially having a single anddefinable number (as a whole number) of monomers rather than a largedistribution. A monodisperse oligomer composition possesses a MW/Mnvalue of 1.0005 or less, and more preferably, a MW/Mn value of 1.0000.By extension, a composition comprised of monodisperse conjugates meansthat substantially all oligomers of all conjugates in the compositionhave a single and definable number (as a whole number) of monomersrather than a large distribution and would possess a MW/Mn value of1.0005, and more preferably, a MW/Mn value of 1,0000 if the oligomerwere not attached to the therapeutic moiety. A composition comprised ofmonodisperse conjugates may, however, include one or more nonconjugatesubstances such as solvents, reagents, excipients, and so forth.

“Bimodal,” in reference to an oligomer composition, refers to anoligomer composition wherein substantially all oligomers in thecomposition have one of two definable and different numbers (as wholenumbers) of monomers rather than a large distribution, and whosedistribution of molecular weights, when plotted as a number fractionversus molecular weight, appears as two separate identifiable peaks.Preferably, for a bimodal oligomer composition as described herein, eachpeak is generally symmetric about its mean, although the size of the twopeaks may differ. Ideally, the polydispersity index of each peak in thebimodal distribution, Mw/Mn, is 1.01 or less, more preferably 1.001 orless, and even more preferably 1,0005 or less, and most preferably aMW/Mn value of 1.0000. By extension, a composition comprised of bimodalconjugates means that substantially all oligomers of all conjugates inthe composition have one of two definable and different numbers (aswhole numbers) of monomers rather than a large distribution and wouldpossess a MW/Mn value of 1.01 or less, more preferably 1.001 or less andeven more preferably 1.0005 or less, and most preferably a MW/Mn valueof 1.0000 if the oligomer were not attached to the therapeutic moiety. Acomposition comprised of bimodal conjugates may, however, include one ormore nonconjugate substances such as solvents, reagents, excipients, andso forth.

A “pyrrolidine moiety” is broadly used herein to refer to an organic,inorganic, or organometallic compound having a molecular weight of lessthan about 1000 Daltons and having some degree of activity as ananti-epileptic and/or analgesic. Assays known to those of ordinary skillin the art can be used to determine whether a given pyrrolidine moiety(as well as a compound provided herein) has activity as ananti-epileptic and/or analgesic.

A “biological membrane” is any membrane made of cells or tissues thatserves as a barrier to at least some foreign entities or otherwiseundesirable materials. As used herein a “biological membrane” includesthose membranes that are associated with physiological protectivebarriers including, for example: the blood-brain barrier (BBB); theblood-cerebrospinal fluid barrier; the blood-placental barrier; theblood-milk barrier; the blood-testes barrier; and mucosal barriersincluding the vaginal mucosa, urethral mucosa, anal mucosa, buccalmucosa, sublingual mucosa, and rectal mucosa. Unless the context clearlydictates otherwise, the term “biological membrane” does not includethose membranes associated with the middle gastro-intestinal tract(e.g., stomach and small intestines).

A “biological membrane crossing rate,” provides a measure of acompound's ability to cross a biological membrane, such as theblood-brain barrier (“BBB”). A variety of methods may be used to assesstransport of a molecule across any given biological membrane. Methods toassess the biological membrane crossing rate associated with any givenbiological barrier (e.g., the blood-cerebrospinal fluid barrier, theblood-placental barrier, the blood-milk barrier, the intestinal barrier,and so forth), are known, described herein and/or in the relevantliterature, and/or may be determined by one of ordinary skill in theart.

A “reduced rate of metabolism” refers to a measurable reduction in therate of metabolism of a water-soluble oligomer-small molecule drugconjugate as compared to the rate of metabolism of the small moleculedrug not attached to the water-soluble oligomer (i.e., the smallmolecule drug itself) or a reference standard material. In the specialcase of “reduced first pass rate of metabolism,” the same “reduced rateof metabolism” is required except that the small molecule drug (orreference standard material) and the corresponding conjugate areadministered orally. Orally administered drugs are absorbed from thegastro-intestinal tract into the portal circulation and may pass throughthe liver prior to reaching the systemic circulation. Because the liveris the primary site of drug metabolism or biotransformation, asubstantial amount of drug may be metabolized before it ever reaches thesystemic circulation. The degree of first pass metabolism, and thus, anyreduction thereof, may be measured by a number of different approaches.For instance, animal blood samples may be collected at timed intervalsand the plasma or serum analyzed by liquid chromatography/massspectrometry for metabolite levels. Other techniques for measuring a“reduced rate of metabolism” associated with the first pass metabolismand other metabolic processes are known, described herein and/or in therelevant literature, and/or may be determined by one of ordinary skillin the art. Preferably, a compound of the invention may provide areduced rate of metabolism [relative to a compound lacking awater-soluble, non-peptidic oligomers) satisfying at least one of thefollowing values: at least about 30%; at least about 40%; at least about50%; at least about 60%; at least about 70%; at least about 80%; and atleast about 90%. A compound (such as a small molecule drug or conjugatethereof) that is “orally bioavailable” is one that preferably possessesa bioavailability when administered orally of greater than 25%, andpreferably greater than 70%, where a compound's bioavailability is thefraction of administered drug that reaches the systemic circulation inunmetabolized form.

“Alkyl” refers to a hydrocarbon chain, ranging from about 1 to 20 atomsin length. Such hydrocarbon chains are preferably but not necessarilysaturated and may be branched or straight chain. Exemplary alkyl groupsinclude methyl, ethyl, propyl, butyl, pentyl, 2-methylbutyl,2-ethylpropyl, 3-methylpentyl, and the like. As used herein, “alkyl”includes cycloalkyl when three or more carbon atoms are referenced. An“alkenyl” group is an alkyl of 2 to 20 carbon atoms with at least onecarbon-carbon double bond.

The terms “substituted alkyl” or “substituted C_(q-r) alkyl” where q andr are integers identifying the range of carbon atoms contained in thealkyl group, denotes the above alkyl groups that are substituted by one,two or three halo (e.g., F, Cl, Br, I), trifluoromethyl, hydroxy, C₁₋₇alkyl (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, t-butyl, and soforth), C₁₋₇ alkoxy, C₁₋₇ acyloxy, C₃₋₇ heterocyclic, amino, phenoxy,nitro, carboxy, acyl, cyano. The substituted alkyl groups may besubstituted once, twice or three times with the same or with differentsubstituents.

“Lower alkyl” refers to an alkyl group containing from 1 to 6 carbonatoms, and may be straight chain or branched, as exemplified by methyl,ethyl, n-butyl, i-butyl, t-butyl. “Lower alkenyl” refers to a loweralkyl group of 2 to 6 carbon atoms having at least one carbon-carbondouble bond.

“Non-interfering substituents” are those groups that, when present in amolecule, are typically non-reactive with other functional groupscontained within the molecule.

“Alkoxy” refers to an —O—R group, wherein R is alkyl or substitutedalkyl, preferably C₁-C₂₀ alkyl (e.g., methoxy, ethoxy, propyloxy, etc.),preferably C₁-C₇.

“Pharmaceutically acceptable excipient” or “pharmaceutically acceptablecarrier” refers to a component that may be included in the compositionsof the invention causes no significant adverse toxicological effects toa patient.

The term “aryl” means an aromatic group having up to 14 carbon atoms.Aryl groups include phenyl, naphthyl, biphenyl, phenanthrenyl,naphthalenyl, and the like. “Substituted phenyl” and “substituted aryl”denote a phenyl group and aryl group, respectively, substituted withone, two, three, four or five (e.g., 1-2, 1-3 or 1-4 substituents)chosen from halo (e.g., F, Cl, Br, I), hydroxy, cyano, nitro, alkyl(e.g., C₁₋₆ alkyl), alkoxy (e.g., C₁₋₆ alkoxy), benzyloxy, carboxy,aryl, and so forth.

Chemical moieties are defined and referred to throughout primarily asunivalent chemical moieties (e.g., alkyl, aryl, etc.). Nevertheless,such terms are also used to convey corresponding multivalent moietiesunder the appropriate structural circumstances clear to those skilled inthe art. For example, while an “alkyl” moiety generally refers to amonovalent radical (e.g., CH₃—CH₂—), in certain circumstances a bivalentlinking moiety can be “alkyl,” in which case those skilled in the artwill understand the alkyl to be a divalent radical (e.g., —CH₂—CH₂—),which is equivalent to the term “alkylene.” (Similarly, in circumstancesin which a divalent moiety is required and is stated as being “aryl,”those skilled in the art will understand that the term “aryl” refers tothe corresponding multivalent moiety, arylene). All atoms are understoodto have their normal number of valences for bond formation (i.e., 1 forH, 4 for carbon, 3 for N, 2 for O, and 2, 4, or 6 for S, depending onthe oxidation state of the S).

“Pharmacologically effective amount,” “physiologically effectiveamount,” and “therapeutically effective amount” are used interchangeablyherein to mean the amount of the compound of the invention present in acomposition that is needed to provide a desired level of the compound(or desired metabolite thereof) in the bloodstream or in the targettissue. The precise amount may depend upon numerous factors, e.g., theparticular active agent, the components and physical characteristics ofthe composition, intended patient population, patient considerations,and may readily be determined by one skilled in the art, based upon theinformation provided herein and available in the relevant literature.

A “difunctional” oligomer is an oligomer having two functional groupscontained therein, typically at its termini. When the functional groupsare the same, the oligomer is said to be homodifunctional. When thefunctional groups are different, the oligomer is said to beheterodifunctional.

A basic reactant or an acidic reactant described herein include neutral,charged, and any corresponding salt forms thereof.

The term “patient,” refers to a living organism suffering from or proneto a condition that can be prevented or treated by administration of acompound of the invention as described herein, and includes both humansand animals.

“Optional” or “optionally” means that the subsequently describedcircumstance may but need not necessarily occur, so that the descriptionincludes instances where the circumstance occurs and instances where itdoes not.

As indicated above, the present invention is directed to (among otherthings) a compound comprising a pyrrolidine residue covalently attachedvia a stable or degradable linkage to a water-soluble, non-peptidicoligomer.

The “pyrrolidine residue” is a compound having a structure of apyrrolidine moiety that is altered by the presence of one or more bonds,which bonds serve to attach (either directly or indirectly) one or morewater-soluble, non-peptidic oligomers. Exemplary pyrrolidine moietieshave a structure encompassed by Formula I:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical; and

either R¹ and R² are each independently selected from the groupconsisting of hydrogen, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, aC₂₋₆ alkynyl radical, a C3-6 cycloalkyl radical, and an aryl radical,

or R¹ and R², together with the nitrogen atom to which they areattached, form a heterocyclic radical.

As previously indicated, the present description (e.g., with respect tocompounds defined by each of Formula Ia-C, Formula Ib-C and Formula I),when (p) is defined as 6 and each “L” is defined as hydrogen, thecorresponding pyrrolidine group will have the following structure:

In one or more embodiments of the invention (e.g., with respect tocompounds defined by each of Formula Ia-C, Formula Ib-C and Formula I),each L is independently selected from the group consisting of hydrogen,hydroxyl and C₁₋₆ alkyl. Further, in one or more embodiments of theinvention (e.g., with respect to compounds defined by each of FormulaIa-C, Formula Ib-C and Formula I), each L is independently selected fromthe group consisting of hydrogen and C₁₋₆ alkyl. Also, in one or moreembodiments of the invention (e.g., with respect to compounds defined byeach of Formula Ia-C, Formula Ib-C and Formula I), one L is hydroxyl andthe remaining L variables are independently selected from the groupconsisting of hydrogen and C₁₋₆ alkyl.

In one or more embodiments of the invention, a compound is provided, thecompound comprising a pyrrolidine residue covalently attached via astable or degradable linkage to a water-soluble, non-peptidic oligomer,wherein the pyrrolidine residue (in a form in which the water-soluble,non-peptidic oligomer is not present) corresponds to a pyrrolidinemoiety selected from the group consisting of levetiracetam, piracetam,brivaracetam, nefiracetam, and oxiracetam. The following list providesthe chemical structures of these and other exemplary pyrrolidinemoieties:

-   (5-methyl-2-oxo-pyrrolidino)-N,N-diethylacetamide;

-   2-(2-oxo-pyrrolidino)-acetamide (also known as “piracetam”);

-   2-(2-oxo-pyrrolidino)-propionamide;

-   (3-methyl-2-oxo-pyrrolidino)-acetamide;

-   2-(5-methyl-2-oxo-pyrrolidino)-butyramide;

-   2-(5-methyl-2-oxo-pyrrolidino)-propionamide;

-   (4-methyl-2-oxo-pyrrolidino)-acetamide;

-   (4-hydroxy-2-oxo-pyrrolidino-acetamide (also known as “oxiracetam”);

-   (5-methyl-2-oxo-pyrrolidino)-acetamide;

-   (3,3-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   (4,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   (4,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   (5,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   (3,5,5-trimethyl-2-oxo-pyrrolidino)-acetamide;

-   2-(2-oxo-pyrrolidino)-butyramide (also known as “etiracetam” in its    racemic form and as “levetiracetam” in its S-enantomeric form);

-   2-(2-oxo-pyrrolidino)-3-methyl-butyramide;

-   (5-ethyl-2-oxo-pyrrolidino)-acetamide;

-   (4,5-dimethyl-2-oxo-pyrrolidino)-N,N-dimethylacetamide;

-   (5,5-dimethyl-2-oxo-pyrrolidino)-N,N-diethylacetamide;

-   2-(2-oxo-pyrrolidino)-3-methyl-butyramide;

-   2-(4-methyl-2-oxo-pyrrolidino)-butyramide;

-   2-(4-propyl-2-oxo-pyrrolidino)-butyramide (also known as    “brivaracetam”);

-   2-(4-methyl-2-oxo-pyrrolidino)-propionamide;

-   2-(4,5-dimethyl-2-oxo-pyrrolidino)-propionamide;

-   N-allyl-(3-methyl-2-oxo-pyrrolidino)-acetamide;

-   N-n-butyl-(3-methyl-2-oxo-pyrrolidino)-acetamide;

-   (3,4-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   (4,4-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   N-n-propyl-(5,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   N-isopropyl-(5,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   N-(2,6-dimethylphenyl)-(2-oxo-pyrrolidino)-acetamide (also known as    “nefiracetam”);

-   N-allyl-(5,5-dimethyl-2-oxo-pyrrolidino)-acetamide;

-   N-propargyl-(5-dimethyl-2-oxo-pyrrolidine)-acetamide;

-   N-n-butyl-2-(5,5-dimethyl-2-oxo-pyrrolidino)-butyramide;

-   N-[(5,5-dimethyl-2-oxo-pyrrolidino)-acetyl]-pyrrolidine;

-   N-[(5,5-dimethyl-2-oxo-pyrrolidino)-acetyl]-piperidine; and

-   N-[(5,5-dimethyl-2-oxo-pyrrolidino)-acetyl]-morpholine.

In some instances, a pyrrolidine moiety that is useful as a startingmaterial or intermediate in synthesizing the compounds of the inventioncan be obtained from commercial sources. In addition, pyrrolidinemoieties can be obtained through chemical synthesis. Further examples ofpyrrolidine moieties, as well as synthetic approaches for preparingpyrrolidine moieties, are described in the literature and in, forexample, U.S. Pat. No. 4,837,223 and Great Britain U.S. Pat. No.1,309,692. Each of these (and other) pyrrolidine moieties can becovalently attached (either directly or through one or more atoms) to awater-soluble, non-peptidic oligomer following the techniques andapproaches described herein.

Exemplary compounds of the invention include those having the followingstructure:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical;

X¹ is a first spacer moiety;

X² is a second spacer moiety;

POLY¹ is a first water-soluble, non-peptidic oligomer; and

POLY² is a second water-soluble, non-peptidic oligomer.

Further exemplary compounds of the invention include those having thefollowing structure:

wherein:

each L is independently selected from the group consisting of hydrogen,hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and a C₂₋₆alkynyl radical;

p is a whole number from 1 to 6;

Y is selected from the group consisting of hydrogen, a C₁₋₆ alkylradical, a C₂₋₆ alkenyl radical, and a C₂₋₆ alkynyl radical;

R² is selected from the group consisting of hydrogen, an alkyl radical,an alkenyl radical, an alkynyl radical, a cycloalkyl radical, and anaryl radical;

X is a spacer moiety; and

POLY is a water-soluble, non-peptidic oligomer.

Use of discrete oligomers (e.g., from a monodisperse or bimodalcomposition of oligomers, in contrast to relatively impure compositions)to form oligomer-containing compounds are preferred. For instance, acompound of the invention, when administered by any of a number ofsuitable administration routes, such as parenteral, oral, transdermal,buccal, pulmonary, or nasal, exhibits reduced penetration across theblood-brain barrier. It is preferred that the compounds of the inventionexhibit slowed, minimal or effectively no crossing of the blood-brainbarrier, while still crossing the gastro-intestinal (GI) walls and intothe systemic circulation if oral delivery is intended. Moreover, thecompounds of the invention maintain a degree of bioactivity as well asbioavailability in comparison to the bioactivity and bioavailability ofthe compound free of all oligomers.

With respect to the blood-brain barrier (“BBB”), this barrier restrictsthe transport of drugs from the blood to the brain. This barrierconsists of a continuous layer of unique endothelial cells joined bytight junctions. The cerebral capillaries, which comprise more than 95%of the total surface area of the BBB, represent the principal route forthe entry of most solutes and drugs into the central nervous system.

For compounds whose degree of blood-brain barrier crossing ability isnot readily known, such ability may be determined using a suitableanimal model such as an in situ rat brain perfusion (“RBP”) model asdescribed herein. Briefly, the RBI technique involves cannulation of thecarotid artery followed by perfusion with a compound solution undercontrolled conditions, followed by a wash out phase to remove compoundremaining in the vascular space. (Such analyses may be conducted, forexample, by contract research organizations such as Absorption Systems,Exton, Pa.). In one example of the REP model, a cannula is placed in theleft carotid artery and the side branches are tied off. A physiologicbuffer containing the analyte (typically but not necessarily at a 5micromolar concentration level) is perfused at a flow rate of about 10mL/minute in a single pass perfusion experiment. After 30 seconds, theperfusion is stopped and the brain vascular contents are washed out withcompound-free buffer for an additional 30 seconds. The brain tissue isthen removed and analyzed for compound concentrations via liquidchromatography with tandem mass spectrometry detection (LC/MS/MS).Alternatively, blood-brain barrier permeability can be estimated basedupon a calculation of the compound's molecular polar surface area(“PSA”), which is defined as the sum of surface contributions of polaratoms (usually oxygens, nitrogens and attached hydrogens) in a molecule.The PSA has been shown to correlate with compound transport propertiessuch as blood-brain barrier transport. Methods for determining acompound's PSA can be found, e.g., Ertl et al. (2000) J. Med. Chem. 43;3714-3717 and Kelder et al. (1999) Pharm. Res. 6:1514-1519.

With respect to the blood-brain barrier, the water-soluble, non-peptidicoligomer-containing compound of the invention exhibits a blood-brainbarrier crossing rate that is reduced as compared to the crossing rateof the small molecule drug not attached to the water-soluble,non-peptidic oligomer. Exemplary reductions in blood-brain barriercrossing rates for the compounds described herein include reductions of:at least about 5%; at least about 10%; at least about 25%; at leastabout 30%; at least about 40%; at least about 50%; at least about 60%;at least about 70%; at least about 80%; or at least about 90%, whencompared to the blood-brain barrier crossing rate of the correspondingcompound lacking water-soluble, non-peptic oligomers. A preferredreduction in the blood-brain barrier crossing rate for a conjugate ofthe invention is at least about 20%.

Assays for determining Whether a given compound (regardless of whetherthe compound includes a water-soluble, non-peptidic oligomer or not) canact as a pyrrolidine moiety are known and/or may be prepared by one ofordinary skill in the art and are further described infra.

Briefly, one approach for testing whether a given pyrrolidine moiety hasa decrease in cerebral excitability (as demonstrated by the audiogenicseizure test in mice) is described in Swinyard et al. (1963) ProceduresInternational Conference on Psychophysiology, Neuropharmacology, andBiochemistry of Audiogenic Seizures Paris, France: InternationalColloquium No. 112; 405-427. Using this approach, preferred pyrolidinemoieties (and compounds of the invention) will be shown to be active inthe tonic phase of the audiogenic seizure at the intraperitoneallyadministered dose of about 200 mg/kg of body weight.

Each of these (and other) pyrrolidine moieties can be covalentlyattached (either directly or through one or more atoms) to awater-soluble, non-peptidic oligomer.

Exemplary molecular weights of a small molecule pyrrolidine moiety(prior to, for example, conjugation to a water-soluble, non-peptidicoligomer) include molecular weights of: less than about 950; less thanabout 900; less than about 850; less than about 800; less than about750; less than about 700; less than about 650; less than about 600; lessthan about 550; less than about 500; less than about 450; less thanabout 400; less than about 350; and less than about 300 Daltons.

The small molecule drug used in the invention, if chiral, may beobtained from a racemic mixture, or an optically active form, forexample, a single optically active enantiomer, or any combination orratio of enantiomers (e.g., scalemic and racemic mixtures). In addition,the small molecule drug may possess one or more geometric isomers. Withrespect to geometric isomers, a composition can comprise a singlegeometric isomer or a mixture of two or more geometric isomers. A smallmolecule drug for use in the present invention can be in its customaryactive form, or may possess some degree of modification. For example, asmall molecule drug may have a targeting agent, tag, or transporterattached thereto, prior to or after covalent attachment of an oligomer.Alternatively, the small molecule drug may possess a lipophilic moietyattached thereto, such as a phospholipid (e.g.,distearoylphosphatidylethanolamine or “DSPE,”dipalmitoylphosphatidylethanolamine or “ppm,” and so forth) or a smallfatty acid. In some instances, however, it is preferred that the smallmolecule drug moiety does not include attachment to a lipophilic moiety.

The pyrrolidine moiety for coupling to a water-soluble, non-peptidicoligomer possesses a free hydroxyl, carboxyl, thio, amino group, or thelike (i.e., “handle”) suitable for covalent attachment to the oligomer.In addition, the pyrrolidine moiety may be modified by introduction of areactive group, preferably by conversion of one of its existingfunctional groups to a functional group suitable for formation of astable covalent linkage between the oligomer and the drug.

Each oligomer is composed of up to three different monomer typesselected from the group consisting of: alkylene oxide, such as ethyleneoxide or propylene oxide; olefinic alcohol, such as vinyl alcohol,1-propenol or 2-propenol; vinyl pyrrolidone; hydroxyalkyl methacrylamideor hydroxyalkyl methacrylate, where alkyl is preferably methyl;α-hydroxy acid, such as lactic acid or glycolic acid; phosphazene,oxazoline, amino acids, carbohydrates such as monosaccharides, alditolsuch as mannitol; and N-acryloylmorpholine. Preferred monomer typesinclude alkylene oxide, olefinic alcohol, hydroxyalkyl methacrylamide ormethacrylate, N-acryloylmorpholine, and α-hydroxy acid. Preferably, eacholigomer is, independently, a co-oligomer of two monomer types selectedfrom this group, or, more preferably, is a homo-oligomer of one monomertype selected from this group.

The two monomer types in a co-oligomer may be of the same monomer type,for example, two alkylene oxides, such as ethylene oxide and propyleneoxide. Preferably, the oligomer is a homo-oligomer of ethylene oxide.Usually, although not necessarily, the terminus (or termini) of theoligomer that is not covalently attached to a small molecule is cappedto render it unreactive. Alternatively, the terminus may include areactive group. When the terminus is a reactive group, the reactivegroup is either selected such that it is unreactive under the conditionsof formation of the final oligomer or during covalent attachment of theoligomer to a small molecule drug, or it is protected as necessary. Onecommon end-functional group is hydroxyl or —OH particularly foroligoethylene oxides.

The water-soluble, non-peptidic oligomer (e.g., “POLY,” “POLY¹” and“POLY²” in various structures provided herein) can have any of a numberof different geometries. For example, the water-soluble, non-peptidicoligomer can be linear, branched, or forked. Most typically, thewater-soluble, non-peptidic oligomer is linear or is branched, forexample, having one branch point. Although much of the discussion hereinis focused upon poly(ethylene oxide) as an illustrative oligomer, thediscussion and structures presented herein can be readily extended toencompass any water-soluble, non-peptidic oligomers described above.

The molecular weight of the water-soluble, non-peptidic oligomer,excluding the linker portion, is generally relatively low. Exemplaryvalues of the molecular weight of the water-soluble polymer include:below about 1500; below about 1450; below about 1400; below about 1350;below about 1300; below about 1250; below about 1200; below about 1150;below about 1100; below about 1050; below about 1000; below about 950;below about 900; below about 850; below about 800; below about 750;below about 700; below about 650; below about 600; below about 550;below about 500; below about 450; below about 400; below about 350;below about 300; below about 250; below about 200; and below about 100Daltons.

Exemplary ranges of molecular weights of the water-soluble, non-peptidicoligomer (excluding the linker) include: from about 100 to about 1400Daltons; from about 100 to about 1200 Daltons; from about 100 to about800 Daltons; from about 100 to about 500 Daltons; from about 100 toabout 400 Daltons; from about 200 to about 500 Daltons; from about 200to about 400 Daltons; from about 75 to 1000 Daltons; and from about 75to about 750 Daltons.

Preferably, the number of monomers in the water-soluble, non-peptidicoligomer falls within one or more of the following ranges: between about1 and about 30 (inclusive); between about 1 and about 25; between about1 and about 20; between about 1 and about 15; between about 1 and about12; between about 1 and about 10. In certain instances, the number ofmonomers in series in the oligomer (and the corresponding conjugate) isone of 1, 2, 3, 4, 5, 6, 7, or 8. In additional embodiments, theoligomer (and the corresponding conjugate) contains 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, or 20 monomers. In yet further embodiments, theoligomer (and the corresponding conjugate) possesses 21, 22, 23, 24, 25,26, 27, 28, 29 or 30 monomers in series. Thus, for example, when thewater-soluble, non-peptidic polymer includes CH₃—(OCH₂CH₂)—, “n” is aninteger that can be 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, and can fallwithin one or more of the following ranges: between about 1 and about25; between about 1 and about 20; between about 1 and about 15; betweenabout 1 and about 12; between about 1 and about 10.

When the water-soluble, non-peptidic oligomer has 1, 2, 3, 4, 5, 6, 7,9, or 10 monomers, these values correspond to a methoxy end-cappedoligo(ethylene oxide) having a molecular weights of about 75, 119, 163,207, 251, 295, 339, 383, 427, and 471 Daltons, respectively. When theoligomer has 11, 12, 13, 14, or 15 monomers, these values correspond tomethoxy end-capped oligo (ethylene oxide) having molecular weightscorresponding to about 515, 559, 603, 647, and 691 Daltons,respectively.

When the water-soluble, non-peptidic oligomer is attached to thepyrrolidine moiety (in contrast to the step-wise addition of one or moremonomers to effectively “grow” the oligomer onto the pyrrolidinemoiety), it is preferred that the composition containing an activatedform of the water-soluble, non-peptidic oligomer be monodisperse. Inthose instances, however, where a bimodal composition is employed, thecomposition will possess a bimodal distribution centering around any twoof the above numbers of monomers. For instance, a bimodal oligomer mayhave any one of the following exemplary combinations of monomersubunits: 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, and so forth;2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, and so forth; 3-4, 3-5, 3-6,3-7, 3-8, 3-9, 3-10, and so forth; 4-5, 4-6, 4-7, 4-8, 4-9, 4-10, and soforth; 5-6, 5-7, 5-8, 5-9, 5-10, and so forth; 6-7, 6-8, 6-9, 6-10, andso forth; 7-8, 7-9, 7-10, and so forth; and 8-9, 8-10, and so forth.

In some instances, the composition containing an activated form of thewater-soluble, non-peptidic oligomer will be trimodal or eventetramodal, possessing a range of monomers units as previouslydescribed. Oligomer compositions possessing a well-defined mixture ofoligomers (i.e., being bimodal, trimodal, tetramodal, and so forth) canbe prepared by mixing purified monodisperse oligomers to obtain adesired profile of oligomers (a mixture of two oligomers differing onlyin the number of monomers is bimodal; a mixture of three oligomersdiffering only in the number of monomers is trimodal; a mixture of fouroligomers differing only in the number of monomers is tetramodal), oralternatively, can be obtained from column chromatography of apolydisperse oligomer by recovering the “center cut”, to obtain amixture of oligomers in a desired and defined molecular weight range.

It is preferred that the water-soluble, non-peptidic oligomer isobtained from a composition that is preferably unimolecular ormonodisperse. That is, the oligomers in the composition possess the samediscrete molecular weight value rather than a distribution of molecularweights. Some monodisperse oligomers can be purchased from commercialsources such as those available from Sigma-Aldrich, or alternatively,can be prepared directly from commercially available starting materialssuch as Sigma-Aldrich. Water-soluble, non-peptidic oligomers can beprepared as described in Chen Y., Baker, G. L., I. Org. Client,6870-6873 (1999), WO 02/098949, and U.S. Patent Application PublicationNo. 2005/0136031.

The spacer moiety (the linkage through which the water-soluble,non-peptidic polymer is attached to the pyrrolidine moiety) may be asingle bond, a single atom, such as an oxygen atom or a sulfur atom, twoatoms, or a number of atoms. A spacer moiety is typically but is notnecessarily linear in nature. The spacer moiety, “X,” is preferablyhydrolytically stable, and is also preferably enzymatically stable.Preferably, the spacer moiety “X” is one having a chain length of lessthan about 12 atoms, and preferably less than about 10 atoms, and evenmore preferably less than about 8 atoms and even more preferably lessthan about 5 atoms, whereby length is meant the number of atoms in asingle chain, not counting substituents. For instance, a urea linkagesuch as this, R_(oligomer)—NH—(C═O)—NH—R′_(drug), is considered to havea chain length of 3 atoms (—NH—C(O)—NH—). In selected embodiments, thelinkage does not comprise further spacer groups.

In some instances, the spacer moiety (e.g., “X,” “X¹” and “X²” invarious structures provided herein) comprises an ether, amide, urethane,amine, thioether, urea, or a carbon-carbon bond. Functional groups suchas those discussed below, and illustrated in the examples, are typicallyused for forming the linkages. The spacer moiety may less preferablyalso comprise (or be adjacent to or flanked by) other atoms, asdescribed further below.

More specifically, in selected embodiments, a spacer moiety (e.g., “X,”“X¹” and “X²” in various structures provided herein) may be any of thefollowing: “-” (i.e., a covalent bond, that may be stable or degradable,between the pyrrolidine residue and the water-soluble, non-peptidicoligomer), —O—, —NH—, —S—, —C(O)—, —C(O)O—, —OC(O)—, —CH₂—C(O)O—,—CH₂—OC(O)—, —C(O)O—CH₂—, —OC(O)—CH₂—, C(O)—NH, NH—C(O)—NH, O—C(O)—NH,—C(S)—, —CH₂—, —CH₂—CH₂—, —CH₂—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—, —O—CH₂—,—CH₂—O—, —O—CH₂—CH₂—, —CH₂—O—CH₂—, —CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—,—CH₂—O—CH₂—CH₂—, —CH₂—CH₂—O—CH₂—, —CH₂—CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—CH₂—,—CH₂—O—CH₂—CH₂—CH₂—, —CH₂—CH₂—O—CH₂—CH₂—, —CH₂—CH₂—CH₂—O—CH₂—,—CH₂—CH₂—CH₂—CH₂—O—, —C(O)—NH—CH₂—, —C(O)—NH—CH₂—CH₂—,—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—C(O)—NH—, —C(O)—NH—CH₂—CH₂—CH₂—,—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—,—C(O)—NH—CH₂—CH₂—CH₂—CH₂—, —CH₂—C(O)—NH—CH₂—CH₂—CH₂—,—CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—,—CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—C(O)—NH—, —NH—C(O)—CH₂—,—CH₂—NH—C(O)—CH₂—, —CH₂—CH₂—NH—C(O)—CH₂—, —NH—C(O)—CH₂—CH₂—,—CH₂—NH—C(O)—CH₂—CH₂, —CH₂—CH₂—NH—C(O)—CH₂—CH₂, —C(O)—NH—CH₂—,—C(O)—NH—CH₂—CH₂—, —O—C(O)—NH—CH₂—, —O—C(O)—NH—CH₂—CH₂—, —NH—CH₂—,—NH—CH₂—CH₂—, —CH₂—NH—CH₂—, —CH₂—CH₂—NH—CH₂—, —C(O)—CH₂—,—C(O)—CH₂—CH₂—, —CH₂—C(O)—CH₂—, —CH₂—CH₂—C(O)—CH₂—,—CH₂—CH₂—C(O)—CH₂—CH₂—, —CH₂—CH₂—C(O)—,—CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—,—CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—CH₂—, bivalent cycloalkyl group,—N(R⁶)—, R⁶ is H or an organic radical selected from the groupconsisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkynyl, substituted alkynyl, aryl and substituted aryl. Additionalspacer moieties include, acylamino, acyl, aryloxy, alkylene bridgecontaining between 1 and 5 inclusive carbon atoms, alkylamino,dialkylamino having about 2 to 4 inclusive carbon atoms, piperidino,pyrrolidino, N-(lower alkyl)-2-piperidyl, morpholino, 1-piperizinyl,4-(lower alkyl)-1-piperizinyl, 4-(hydroxyl-lower alkyl)-1-piperizinyl,4-(methoxy-lower alkyl)-1-piperizinyl, and guanidine. In some instances,a portion or a functional group of the drug compound may be modified orremoved altogether to facilitate attachment of the oligomer. In someinstances, it is preferred that X is not an amide, i.e., —CONR— and—RNCO—.

For purposes of the present invention, however, a group of atoms is notconsidered a linkage when it is immediately adjacent to an oligomersegment, and the group of atoms is the same as a monomer of the oligomersuch that the group would represent a mere extension of the oligomerchain.

The spacer moiety between the water-soluble, non-peptidic oligomer andthe small molecule is formed by reaction of a functional group on aterminus of the oligomer (or nascent oligomer when it is desired to“grow” the oligomer onto the pyrrolidine) with a correspondingfunctional group within the pyrrolidine. Illustrative reactions aredescribed briefly below. For example, an amino group on an oligomer maybe reacted with a carboxylic acid or an activated carboxylic acidderivative on the small molecule, or vice versa, to produce an amidelinkage. Alternatively, reaction of an amine on an oligomer with anactivated carbonate (e.g., succinimidyl or benzotriazolyl carbonate) onthe drug, or vice versa, forms a carbamate linkage. Reaction of an amineon an oligomer with an isocyanate (R—N═C═O) on a drug, or vice versa,forms a urea linkage (R—NH—(C═O)—NH—R′). Further, reaction of an alcohol(alkoxide) group on an oligomer with an alkyl halide, or halide groupwithin a drug, or vice versa, forms an ether linkage. In yet anothercoupling approach, a small molecule having an aldehyde function iscoupled to an oligomer amino group by reductive amination, resulting information of a secondary amine linkage between the oligomer and thesmall molecule.

A particularly preferred water-soluble, non-peptidic oligomer is anoligomer bearing an aldehyde functional group. In this regard, theoligomer will have the following structure:CH₃O—(CH₂—CH₂—O)_(n)—(CH₂)_(p)—C(O)H, wherein (n) is one of 1, 2, 3, 4,5, 6, 7, 8, 9 and 10 and (p) is one of 1, 2, 3, 4, 5, 6 and 7. Preferred(n) values include 3, 5 and 7 and preferred (p) values 2, 3 and 4.

The termini of the water-soluble, non-peptidic oligomer not bearing afunctional group may be capped to render it unreactive. When theoligomer includes a further functional group at a terminus other thanthat intended for formation of a conjugate, that group is eitherselected such that it is unreactive under the conditions of formation ofthe spacer moiety (e.g., “X”) or it is protected during the formation ofthe spacer moiety (e.g., “X”).

As stated above, the water-soluble, non-peptidic oligomer includes atleast one functional group prior to conjugation. The functional groupcomprises an electrophilic or nucleophilic group for covalent attachmentto a small molecule, depending upon the reactive group contained withinor introduced into the small molecule. Examples of nucleophilic groupsthat may be present in either the oligomer or the small molecule includehydroxyl, amine, hydrazine (—NHNH₂), hydrazide (—C(O)NHNH₂), and thiol.Preferred nucleophiles include amine, hydrazine, hydrazide, and thiol,particularly amine. Most small molecule drugs for covalent attachment toan oligomer will possess a free hydroxyl, amino, thio, aldehyde, ketone,or carboxyl group.

Examples of electrophilic functional groups that may be present ineither the oligomer or the small molecule include carboxylic acid,carboxylic ester, particularly imide esters, orthoester, carbonate,isocyanate, isothiocyanate, aldehyde, ketone, thione, alkenyl, acrylate,methacrylate, acrylamide, sulfone, maleimide, disulfide, iodo, epoxy,sulfonate, thiosulfonate, silane, alkoxysilane, and halosilane. Morespecific examples of these groups include succinimidyl ester orcarbonate, imidazoyl ester or carbonate, benzotriazole ester orcarbonate, vinyl sulfone, chloroethylsulfone, vinylpyridine, pyridyldisulfide, iodoacetamide, glyoxal, dime, mesylate, tosylate, andtresylate (2,2,2-trifluoroethanesulfonate).

Also included are sulfur analogs of several of these groups, such asthione, thione hydrate, thioketal, 2-thiazolidine thione, etc., as wellas hydrates or protected derivatives of any of the above moieties (e.g.,aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, ketal,thioketal, thioacetal).

An “activated derivative” of a carboxylic acid refers to a carboxylicacid derivative that reacts readily with nucleophiles, generally muchmore readily than the underivatized carboxylic acid, Activatedcarboxylic acids include, for example, acid halides (such as acidchlorides), anhydrides, carbonates, and esters. Such esters includeimide esters, of the general form —(CO)O—N[(CO)—]₂; for example,N-hydroxysuccinimidyl (NHS) esters or N-hydroxyphthalimidyl esters. Alsopreferred are imidazolyl esters and benzotriazole esters. Particularlypreferred are activated propionic acid or butanoic acid esters, asdescribed in co-owned U.S. Pat. No. 5,672,662. These include groups ofthe form —(CH₂)₂₋₃C(═O)O-Q, where Q is preferably selected fromN-succinimide, N-sulfosuccinimide, N-phthalimide, N-glutarimide,N-tetrahydrophthalimide, N-norbornene-2,3-dicarboximide, benzotriazole,7-azabenzotriazole, and imidazole.

Other preferred electrophilic groups include succinimidyl carbonate,maleimide, benzotriazole carbonate, glycidyl ether, imidazoyl carbonate,p-nitrophenyl carbonate, acrylate, tresylate, aldehyde, and orthopyridyldisulfide.

These electrophilic groups are subject to reaction with nucleophiles,e.g., hydroxy, thio, or amino groups, to produce various bond types.Preferred for the present invention are reactions which favor formationof a hydrolytically stable linkage. For example, carboxylic acids andactivated derivatives thereof, which include orthoesters, succinimidylesters, imidazolyl esters, and benzotriazole esters, react with theabove types of nucleophiles to form esters, thioesters, and amides,respectively, of which amides are the most hydrolytically stable.Carbonates, including succinimidyl, imidazolyl, and benzotriazolecarbonates, react with amino groups to form carbamates. Isocyanates(R—N═C═O) react with hydroxyl or amino groups to form, respectively,carbamate (RNH—C(O)—OR′) or urea (RNH—C(O)—NHR′) linkages. Aldehydes,ketones, glyoxals, diones and their hydrates or alcohol adducts (i.e.,aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, andketal) are preferably reacted with amines, followed by reduction of theresulting imine, if desired, to provide an amine linkage (reductiveamination).

Several of the electrophilic functional groups include electrophilicdouble bonds to which nucleophilic groups, such as thiols, can be added,to form, for example, thioether bonds. These groups include maleimides,vinyl sulfones, vinyl pyridine, acrylates, methacrylates, andacrylamides. Other groups comprise leaving groups that can be displacedby a nucleophile; these include chloroethyl sulfone, pyridyl disulfides(which include a cleavable S—S bond), iodoacetamide, mesylate, tosylate,thiosulfonate, and tresylate. Epoxides react by ring opening by anucleophile, to form, for example, an ether or amine bond. Reactionsinvolving complementary reactive groups such as those noted above on theoligomer and the small molecule are utilized to prepare the conjugatesof the invention.

In some instances the pyrrolidine moiety may not have a functional groupsuited for conjugation. In this instance, it is possible to modify (or“functionalize”) the “original” pyrrolidine moiety so that it does havea functional group suited for conjugation. For example, if thepyrrolidine moiety has an amide group, but an amine group is desired, itis possible to modify the amide group to an amine group by way of aHofmann rearrangement, Curtius rearrangement (once the amide isconverted to an azide) or Lossen rearrangement (once amide is concertedto hydroxamide followed by treatment with tolyene-2-sulfonylchloride/base).

It is possible to prepare a conjugate of pyrrolidine moiety bearing acarboxyl group wherein the carboxyl group-bearing pyrrolidine moiety iscoupled to an amino-terminated oligomeric ethylene glycol, to provide aconjugate having an amide group covalently linking the pyrrolidinemoiety to the oligomer. This can be performed, for example, by combiningthe carboxyl group-bearing pyrrolidine moiety with the amino-terminatedoligomeric ethylene glycol in the presence of a coupling reagent, (suchas dicyclohexylcarbodiimide or “DCC”) in an anhydrous organic solvent.

Further, it is possible to prepare a conjugate of a pyrrolidine moietybearing a hydroxyl group wherein the hydroxyl group-bearing pyrrolidinemoiety is coupled to an oligomeric ethylene glycol halide to result inan ether (—O—) linked conjugate. This can be performed, for example, byusing sodium hydride to deprotonate the hydroxyl group followed byreaction with a halide-terminated oligomeric ethylene glycol.

Further, it is possible to prepare a conjugate of a pyrrolidine moietybearing a hydroxyl group wherein the hydroxyl group-bearing pyrrolidinemoiety is coupled to an oligomeric ethylene glycol bearing anhaloformate group [e.g., CH₃(OCH₂CH₂)_(n)OC(O)-halo, where halo ischloro, bromo, iodo] to result in a carbonate [—O—C(O)—O—] linked smallmolecule conjugate. This can be performed, for example, by combining apyrrolidine moiety and an oligomeric ethylene glycol bearing ahaloformate group in the presence of a nucleophilic catalyst (such as4-dimethylaminomidine or “DMAP”) to thereby result in the correspondingcarbonate-linked conjugate.

In another example, it is possible to prepare a conjugate of apyrrolidine moiety bearing a ketone group by first reducing the ketonegroup to form the corresponding hydroxyl group. Thereafter, thepyrrolidine moiety now bearing a hydroxyl group can be coupled asdescribed herein.

In still another instance, it is possible to prepare a conjugate of apyrrolidine moiety bearing an amine group. In one approach, the aminegroup-bearing pyrrolidine moiety and an aldehyde-bearing oligomer aredissolved in a suitable buffer after which a suitable reducing agent(e.g., NaCNBH₃) is added. Following reduction, the result is an aminelinkage formed between the amine group of the amine group-containingpyrrolidine moiety and the carbonyl carbon of the aldehyde-bearingoligomer.

In another approach for preparing a conjugate of a pyrrolidine moietybearing an amine group, a carboxylic acid-bearing oligomer and the aminegroup-bearing pyrrolidine moiety are combined, in the presence of acoupling reagent (e.g., DCC). The result is an amide linkage formedbetween the amine group of the amine group-containing pyrrolidine moietyand the carbonyl of the carboxylic acid-bearing oligomer.

While it is believed that the full scope of the compounds disclosedherein behave as described, an optimally sized oligomer can beidentified as follows.

First, an oligomer obtained from a monodisperse or bimodal water solubleoligomer is conjugated to the pyrrolidine moiety. Preferably, the drugis orally bioavailable, and on its own, exhibits a non-negligibleblood-brain barrier crossing rate. Next, the ability of the conjugate tocross the blood-brain barrier is determined using an appropriate modeland compared to that of the unmodified parent drug. If the results arefavorable, that is to say, if, for example, the rate of crossing issignificantly reduced, then the bioactivity of conjugate is furtherevaluated. Preferably, the compounds according to the invention maintaina significant degree of bioactivity relative to the parent drug, i.e.,greater than about 30% of the bioactivity of the parent drug, or evenmore preferably, greater than about 50% of the bioactivity of the parentdrug.

The above steps are repeated one or more times using oligomers of thesame monomer type but having a different number of subunits and theresults compared.

For each conjugate whose ability to cross the blood-brain barrier isreduced in comparison to the non-conjugated small molecule drug, itsoral bioavailability is then assessed. Based upon these results, that isto say, based upon the comparison of conjugates of oligomers of varyingsize to a given small molecule at a given position or location withinthe small molecule, it is possible to determine the size of the oligomermost effective in providing a conjugate having an optimal balancebetween reduction in biological membrane crossing, oral bioavailability,and bioactivity. The small size of the oligomers makes such screeningsfeasible and allows one to effectively tailor the properties of theresulting conjugate. By making small, incremental changes in oligomersize and utilizing an experimental design approach, one can effectivelyidentify a conjugate having a favorable balance of reduction inbiological membrane crossing rate, bioactivity, and oralbioavailability. In some instances, attachment of an oligomer asdescribed herein is effective to actually increase oral bioavailabilityof the drug.

For example, one of ordinary skill in the art, using routineexperimentation, can determine a best suited molecular size and linkagefor improving oral bioavailability by first preparing a series ofoligomers with different weights and functional groups and thenobtaining the necessary clearance profiles by administering theconjugates to a patient and taking periodic blood and/or urine sampling.Once a series of clearance profiles have been obtained for each testedconjugate, a suitable conjugate can be identified.

Animal models (rodents and dogs) can also be used to study oral drugtransport. In addition, non-in vivo methods include rodent everted gutexcised tissue and Caco-2 cell monolayer tissue-culture models. Thesemodels are useful in predicting oral drug bioavailability.

To determine whether the pyrrolidine moiety or a compound of theinvention (e.g., a conjugate of a pyrrolidine moiety and awater-soluble, non-peptidic oligomer) has activity as a pyrrolidinemoiety therapeutic, it is possible to test such a compound. The compoundof interest may be tested using in vitro binding studies to receptorsusing various cell lines expressing these receptors that have becomeroutine in pharmaceutical industry and described herein.

The compounds of the invention may be administered per se or in the formof a pharmaceutically acceptable salt, and any reference to thecompounds of the invention herein is intended to includepharmaceutically acceptable salts. If used, a salt of a compound asdescribed herein should be both pharmacologically and pharmaceuticallyacceptable, but non-pharmaceutically acceptable salts may convenientlybe used to prepare the free active compound or pharmaceuticallyacceptable salts thereof and are not excluded from the scope of thisinvention. Such pharmacologically and pharmaceutically acceptable saltscan be prepared by reaction of the compound with an organic or inorganicacid, using standard methods detailed in the literature. Examples ofuseful salts include, but are not limited to, those prepared from thefollowing acids: hydrochloric, hydrobromic, sulfuric, nitric,phosphoric, maleic, acetic, salicyclic, p-toluenesulfonic, tartaric,citric, methanesulfonic, formic, malonic, succinic,naphthalene-2-sulphonic and benzenesulphonic, and the like. Also,pharmaceutically acceptable salts can be prepared as alkaline metal oralkaline earth salts, such as sodium, potassium, or calcium salts of acarboxylic acid group.

The present invention also includes pharmaceutical preparationscomprising a compound as provided herein in combination with apharmaceutical excipient. Generally, the compound itself will be in asolid form (e.g., a precipitate), which can be combined with a suitablepharmaceutical excipient that can be in either solid or liquid form.

Exemplary excipients include, without limitation, those selected fromthe group consisting of carbohydrates, inorganic salts, antimicrobialagents, antioxidants, surfactants, buffers, acids, bases, andcombinations thereof.

A carbohydrate such as a sugar, a derivatized sugar such as an alditol,aldonic acid, an esterified sugar, and/or a sugar polymer may be presentas an excipient. Specific carbohydrate excipients include, for example:monosaccharides, such as fructose, maltose, galactose, glucose,D-mannose, sorbose, and the like; disaccharides, such as lactose,sucrose, trehalose, cellobiose, and the like; polysaccharides, such asraffinose, melezitose, maltodextrins, dextrans, starches, and the like;and alditols, such as mannitol, maltitol, lactitol, xylitol, sorbitol,myoinositol, and the like.

The excipient can also include an inorganic salt or buffer such ascitric acid, sodium chloride, potassium chloride, sodium sulfate,potassium nitrate, sodium phosphate monobasic, sodium phosphate dibasic,and combinations thereof.

The preparation may also include an antimicrobial agent for preventingor deterring microbial growth. Nonlimiting examples of antimicrobialagents suitable for the present invention include benzalkonium chloride,benzethonium chloride, benzyl alcohol, cetylpyridinium chloride,chlorobutanol, phenol, phenylethyl alcohol, phenylmercuric nitrate,thimersol, and combinations thereof.

An antioxidant can be present in the preparation as well. Antioxidantsare used to prevent oxidation, thereby preventing the deterioration ofthe conjugate or other components of the preparation. Suitableantioxidants for use in the present invention include, for example,ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene,hypophosphorous acid, monothioglycerol, propyl gallate, sodiumbisulfite, sodium formaldehyde sulfoxylate, sodium metabisulfite, andcombinations thereof.

A surfactant may be present as an excipient. Exemplary surfactantsinclude: polysorbates, such as “Tween 20” and “Tween 80,” and pluronicssuch as F68 and F88 (both of which are available from BASF, Mount Olive,N.J.); sorbitan esters; lipids, such as phospholipids such as lecithinand other phosphatidylcholines, phosphatidylethanolamines, fatty acidsand fatty esters; steroids, such as cholesterol; and chelating agents,such as EDTA, zinc and other such suitable cations.

Pharmaceutically acceptable acids or bases may be present as anexcipient in the preparation. Nonlimiting examples of acids that can beused include those acids selected from the group consisting ofhydrochloric acid, acetic acid, phosphoric acid, citric acid, malicacid, lactic acid, formic acid, trichloroacetic acid, nitric acid,perchloric acid, phosphoric acid, sulfuric acid, fumaric acid, andcombinations thereof. Examples of suitable bases include, withoutlimitation, bases selected from the group consisting of sodiumhydroxide, sodium acetate, ammonium hydroxide, potassium hydroxide,ammonium acetate, potassium acetate, sodium phosphate, potassiumphosphate, sodium citrate, sodium formate, sodium sulfate, potassiumsulfate, potassium fumerate, and combinations thereof.

The amount of the compound of the invention in the composition will varydepending on a number of factors, but will optimally be atherapeutically effective dose when the composition is stored in a unitdose container. A therapeutically effective dose can be determinedexperimentally by repeated administration of increasing amounts of thecompound in order to determine which amount produces a clinicallydesired endpoint.

The amount of any individual excipient in the composition will varydepending on the activity of the excipient and particular needs of thecomposition. The optimal amount of any individual excipient isdetermined through routine experimentation, i.e., by preparingcompositions containing varying amounts of the excipient (ranging fromlow to high), examining the stability and other parameters, and thendetermining the range at which optimal performance is attained with nosignificant adverse effects.

Generally, however, excipients will be present in the composition in anamount of about 1% to about 99% by weight, preferably from about 5%-98%by weight, more preferably from about 15-95% by weight of the excipient,with concentrations less than 30% by weight most preferred.

These foregoing pharmaceutical excipients along with other excipientsand general teachings regarding pharmaceutical compositions aredescribed in “Remington: The Science & Practice of Pharmacy”, 19^(th)ed., Williams & Williams, (1995), the “Physician's Desk Reference”,52^(nd), Medical Economics, Montvale, N J (1998), and Kibbe, A. H.,Handbook of Pharmaceutical Excipients, 3^(rd) Edition, AmericanPharmaceutical Association, Washington, D.C., 2000.

The pharmaceutical compositions can take any number of forms and theinvention is not limited in this regard. Exemplary preparations are mostpreferably in a form suitable for oral administration such as a tablet,caplet, capsule, gel cap, troche, dispersion, suspension, solution,elixir, syrup, lozenge, transdermal patch, spray, suppository, andpowder.

Oral dosage forms are preferred for those conjugates that are orallyactive, and include tablets, caplets, capsules, gel caps, suspensions,solutions, elixirs, and syrups, and can also comprise a plurality ofgranules, beads, powders or pellets that are optionally encapsulated.Such dosage forms are prepared using conventional methods known to thosein the field of pharmaceutical formulation and described in thepertinent texts.

Tablets and caplets, for example, can be manufactured using standardtablet processing procedures and equipment. Direct compression andgranulation techniques are preferred when preparing tablets or capletscontaining the conjugates described herein. In addition to theconjugate, the tablets and caplets will generally contain inactive,pharmaceutically acceptable carrier materials such as binders,lubricants, disintegrants, fillers, stabilizers, surfactants, coloringagents, flow agents, and the like. Binders are used to impart cohesivequalities to a tablet, and thus ensure that the tablet remains intact.Suitable binder materials include, but are not limited to, starch(including corn starch and pregelatinized starch), gelatin, sugars(including sucrose, glucose, dextrose and lactose), polyethylene glycol,waxes, and natural and synthetic gums, e.g., acacia sodium alginate,polyvinylpyrrolidone, cellulosic polymers (including hydroxypropylcellulose, hydroxypropyl methylcellulose, methyl cellulose,microcrystalline cellulose, ethyl cellulose, hydroxyethylcellulose, andthe like), and Veegum. Lubricants are used to facilitate tabletmanufacture, promoting powder flow and preventing particle capping(i.e., particle breakage) when pressure is relieved. Useful lubricantsare magnesium stearate, calcium stearate, and stearic acid.Disintegrants are used to facilitate disintegration of the tablet, andare generally starches, clays, celluloses, algins, gums, or crosslinkedpolymers. Fillers include, for example, materials such as silicondioxide, titanium dioxide, alumina, talc, kaolin, powdered cellulose,and microcrystalline cellulose, as well as soluble materials such asmannitol, urea, sucrose, lactose, dextrose, sodium chloride, andsorbitol. Stabilizers, as well known in the art, are used to inhibit orretard drug decomposition reactions that include, by way of example,oxidative reactions.

Capsules are also preferred oral dosage forms, in which case theconjugate-containing composition can be encapsulated in the form of aliquid or gel (e.g., in the case of a gel cap) or solid (includingparticulates such as granules, beads, powders or pellets). Suitablecapsules include hard and soft capsules, and are generally made ofgelatin, starch, or a cellulosic material. Two-piece hard gelatincapsules are preferably sealed, such as with gelatin bands or the like.

Included are parenteral formulations in the substantially dry form (as alyophilizate or precipitate, which can be in the form of a powder orcake), as well as formulations prepared for injection, which are liquidand require the step of reconstituting the dry form of parenteralformulation. Examples of suitable diluents for reconstituting solidcompositions prior to injection include bacteriostatic water forinjection, dextrose 5% in water, phosphate-buffered saline, Ringer'ssolution, saline, sterile water, deionized water, and combinationsthereof.

In some cases, compositions intended for parenteral administration cantake the form of nonaqueous solutions, suspensions, or emulsions,normally being sterile. Examples of nonaqueous solvents or vehicles arepropylene glycol, polyethylene glycol, vegetable oils, such as olive oiland corn oil, gelatin, and injectable organic esters such as ethyloleate.

The parenteral formulations described herein can also contain adjuvantssuch as preserving, wetting, emulsifying, and dispersing agents. Theformulations are rendered sterile by incorporation of a sterilizingagent, filtration through a bacteria-retaining filter, irradiation, orheat.

The compounds of the invention can also be administered through the skinusing conventional transdermal patch or other transdermal deliverysystem, wherein the conjugate is contained within a laminated structurethat serves as a drug delivery device to be affixed to the skin. In sucha structure, the compound is contained in a layer, or “reservoir,”underlying an upper backing layer. The laminated structure can contain asingle reservoir, or it can contain multiple reservoirs.

The compounds of the invention can also be formulated into a suppositoryfor rectal administration. With respect to suppositories, the compoundis mixed with a suppository base material which is (e.g., an excipientthat remains solid at room temperature but softens, melts or dissolvesat body temperature) such as coca butter (theobroma oil), polyethyleneglycols, glycerinated gelatin, fatty acids, and combinations thereof.Suppositories can be prepared by, for example, performing the followingsteps (not necessarily in the order presented); melting the suppositorybase material to form a melt; incorporating the compound (either beforeor after melting of the suppository base material); pouring the meltinto a mold; cooling the melt (e.g., placing the melt-containing mold ina room temperature environment) to thereby form suppositories; andremoving the suppositories from the mold.

In some embodiments of the invention, the compositions comprising thecompounds of the invention may further be incorporated into a suitabledelivery vehicle. Such delivery vehicles may provide controlled and/orcontinuous release of the compounds and may also serve as a targetingmoiety. Non-limiting examples of delivery vehicles include, adjuvants,synthetic adjuvants, microcapsules, microparticles, liposomes, and yeastcell wall particles. Yeast cells walls may be variously processed toselectively remove protein component, glucan, or mannan layers, and arereferred to as whole glucan particles (WGP), yeast beta-glucan mannanparticles (YGMP), yeast Oilcan particles (YUP), Rhodotorula yeast cellparticles (YCP). Yeast cells such as S. cerevisiae and Rhodotorulaspecies are preferred; however, any yeast cell may be used. These yeastcells exhibit different properties in terms of hydrodynamic volume andalso differ in the target organ where they may release their contents.The methods of manufacture and characterization of these particles aredescribed in U.S. Pat. Nos. 5,741,495, 4,810,646, 4,992,540, 5,028,703and 5,607,677, and U.S. Patent Application Publication Nos. 2005/0281781and 2008/0044438.

The invention also provides a method for administering a compound of theinvention as provided herein to a patient suffering from a conditionthat is responsive to treatment with the compound. The method comprisesadministering, generally orally, a therapeutically effective amount ofthe compound (preferably provided as part of a pharmaceuticalpreparation). Other modes of administration are also contemplated, suchas pulmonary, nasal, buccal, rectal, sublingual, transdermal, andparenteral. As used herein, the term “parenteral” includes subcutaneous,intravenous, intra-arterial, intraperitoneal, intracardiac, intrathecal,and intramuscular injection, as well as infusion injections.

In instances where parenteral administration is utilized, it may benecessary to employ somewhat bigger oligomers than those describedpreviously, with molecular weights ranging from about 500 to 30K Daltons(e.g., having molecular weights of about 500, 1000, 2000, 2500, 3000,5000, 7500, 10000, 15000, 20000, 25000, 30000 or even more).

The method of administering may be used to treat any condition that canbe remedied or prevented by administration of a particular compound ofthe invention. Those of ordinary skill in the art appreciate whichconditions a specific compound can effectively treat. Exemplaryconditions include epileptic conditions and pain. The actual dose to beadministered will vary depend upon the age, weight, and generalcondition of the subject as well as the severity of the condition beingtreated, the judgment of the health care professional, and conjugatebeing administered. Therapeutically effective amounts are known to thoseskilled in the art and/or are described in the pertinent reference textsand literature. Generally, a therapeutically effective amount will rangefrom about 0.001 mg to 1000 mg, preferably in doses from 0.01 mg/day to750 mg/day, and more preferably in doses from 0.10 mg/day to 500 mg/day.

The unit dosage of any given compound of the invention (again,preferably provided as part of a pharmaceutical preparation) can beadministered in a variety of dosing schedules depending on the judgmentof the clinician, needs of the patient, and so forth. The specificdosing schedule will be known by those of ordinary skill in the art orcan be determined experimentally using routine methods. Exemplary dosingschedules include, without limitation, administration five times a day,four times a day, three times a day, twice daily, once daily, threetimes weekly, twice weekly, once weekly, twice monthly, once monthly,and any combination thereof. Once the clinical endpoint has beenachieved, dosing of the composition is halted.

All articles, books, patents, patent publications and other publicationsreferenced herein are incorporated by reference in their entireties. Inthe event of an inconsistency between the teachings of thisspecification and the art incorporated by reference, the meaning of theteachings and definitions in this specification shall prevail(particularly with respect to terms used in the claims appended herein).For example, where the present application and a publicationincorporated by reference defines the same term differently, thedefinition of the term shall be preserved within the teachings of thedocument from which the definition is located.

EXPERIMENTAL

It is to be understood that while the invention has been described inconjunction with certain preferred and specific embodiments, theforegoing description as well as the examples that follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

All non-PEG chemical reagents referred to in the appended examples arecommercially available unless otherwise indicated. The preparation ofPEG-mers is described in, for example, U.S. Patent ApplicationPublication No. 2005/0136031.

¹H NMR (nuclear magnetic resonance) data was generated by an NMRspectrometer.

Example 1 Synthesis of Compounds Based on Levetiracetam

An exemplary approach for preparing compounds of the invention based onlevetiracetam is provided schematically directly above. Briefly,levetiracetam (1) (118 mg, 0.5 mmol) is dissolved in 5 nil THF, and NaH(60%, 60 mg, 1.5 mmol) is added to the solution. The mixture is stirredfor 5 minutes before mPEG_(n)-Br [n=1-11] (0.6 mmol) is added. Theresulting mixture is stirred at room temperature for 14 hours. Thesolids are removed and 150 ml dichloromethane is added. The organicphase is washed with H₂O (2×150 mL), dried over Na₂SO₄ and solvent isremoved under reduced pressure. The crude product is a mixture ofcompounds (2) and (3), which correspond to compounds of the inventionhaving a single water-soluble, non-peptidic oligomer and compounds ofthe invention having two water-soluble, non-peptidic oligomers,respectively. The crude product is purified by column chromatography.

What is claimed is:
 1. A compound comprising a pyrrolidone residuecovalently attached to two water-soluble, non-peptidic oligomers, thecompound having the following structure,

wherein; each L is independently selected from the group consisting ofhydrogen, hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and aC₂₋₆ alkynyl radical; p is a whole number from 1 to 6; Y is selectedfrom the group consisting of hydrogen, a C₁₋₆ alkyl radical, a C₂₋₆alkenyl radical, and a C₂₋₆ alkynyl radical; X¹ is a first spacermoiety; X² is a second spacer moiety; POLY¹ is a first water-soluble,non-peptidic oligomer having a molecular weight of below about 1500Daltons; and POLY² is a second water-soluble, non-peptidic oligomerhaving a molecular weight of below about 1500 Daltons, andpharmaceutically acceptable salts thereof.
 2. The compound of claim 1,wherein the pyrrolidine residue is a residue of a pyrrolidine moietyencompassed within the formula:

wherein: each L is independently selected from the group consisting ofhydrogen, hydroxyl, a C₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, and aC₂₋₆ alkynyl radical; p is a whole number from 1 to 6; Y is selectedfrom the group consisting of hydrogen, a C₁₋₆ alkyl radical, a C₂₋₆alkenyl radical, and a C₂₋₆ alkynyl radical; and either R¹ and R² areeach independently selected from the group consisting of hydrogen, aC₁₋₆ alkyl radical, a C₂₋₆ alkenyl radical, a C₂₋₆ alkynyl radical, aC₃₋₆ cycloalkyl radical, and an aryl radical, or R¹ and R², togetherwith the nitrogen atom to which they are attached, form a heterocyclicradical.
 3. The compound of claim 1, wherein the pyrrolidine residue isa residue of a pyrrolidine moiety selected from the group consisting oflevetiracetam, piracetam, brivaracetam, nefiracetam and oxiracetam. 4.The compound of claim 3, wherein the pyrrolidine residue is a residue ofa pyrrolidine moiety selected from the group consisting oflevetiracetam, piracetam, brivaracetam and nefiracetam.
 5. The compoundof claim 4, wherein the pyrrolidine residue is a residue oflevetiracetam.
 6. The compound of claim 1, wherein each of thewater-soluble, non-peptidic oligomers is a poly(alkylene oxide).
 7. Thecompound of claim 6, wherein each of the poly(alkylene oxide)s is apoly(ethylene oxide).
 8. The compound of claim 1, wherein each of thewater-soluble, non-peptidic oligomers has from about 1 to about 30monomers.
 9. The compound of claim 1, wherein each of the water-soluble,non-peptidic oligomers has from about 1 to about 10 monomers.
 10. Thecompound of claim 7, wherein each of the poly(alkylene oxide)s includesan alkoxy or hydroxy end-capping moiety.
 11. The compound of claim 1,wherein the pyrrolidone residue is covalently attached to the twowater-soluble, non-peptidic oligomers via a stable linkage.